Method for producing a transparent or translucent vehicle part

Abstract

The invention relates to a method for manufacturing a bodywork part (2) of a motor vehicle, characterized in that it comprises the following steps: - depositing at least one opaque coating on at least a portion of a face (6) of a main body (3) of the bodywork part (2), the main body (3) being made of transparent or translucent plastic material, and - producing a set of microperforations (8, 10) of the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, an irradiation path (12, 16, 22) of the laser beam consisting solely of successive substantially rectilinear path lines (12', 16', 22').

Description

[0001] The invention relates to a motor vehicle part. More particularly, the invention relates to a method for manufacturing a transparent or translucent vehicle part contributing to the exterior appearance of the vehicle and a device for carrying out such a method.

[0002] A vehicle includes several transparent or translucent parts intended to transmit light. These include parts used for regulatory lighting purposes, such as those protecting the headlight units for the main and dipped beam headlights or the indicator lights. In addition, the vehicle may also have light sources intended for decorative purposes that enhance the vehicle's aesthetics.

[0003] For these purposes, it is possible to treat an external surface or an internal face of the transparent or translucent plastic parts in order to improve their appearance. One possibility for doing this is to overmould an opaque film or mask onto the external surface of the part, the opaque film having a predefined pattern allowing the passage of light. In this way, when the light source associated with the part emits light, the latter is partially blocked by the opacity of the opaque film and partially transmitted by the parts of the part which are opposite the pattern. This makes it possible to improve the aesthetics of the light beam transmitted, by the transparent or translucent part, from the light source to the external environment. An opaque film as described above can cause problems of colour matching with the paint of the other parts of the vehicle, which has a negative impact on the aesthetics of the vehicle.

[0004] It is also known to paint the external or internal face of a transparent or translucent body panel and then remove a more or less significant part of the applied paint layer, for example by making micro-perforations or larger areas using a laser on the paint layer in order to clear areas of any paint and make them transparent or translucent. The aim is to allow light to pass through from behind the body part.

[0005] In the case of microperforations, the latter are sized and distributed on the body panel so as to allow visible light emitted from an internal face of the body panel to pass to the exterior of the body panel while not allowing, when the light source(s) are off, to see through the body panel from the exterior of the vehicle while maintaining an overall appearance close to a painted body part without removal of paint from the body part due to the small size of the microperforations.

[0006] The microperforations made using a laser are typically substantially circular in shape and the number of microperforations can be relatively large on a treated surface. Indeed, the areas capable of letting light pass through can measure from a few centimeters to several tens of centimeters and the microperforations can have a size ranging from 20 to 1000 micrometers, preferably between 50 and 700 micrometers, preferably between 100 and 300 micrometers, and can be spaced apart from each other by a distance of between 1 and 4 times the size of the microperforations, preferably between 2 and 3 times the size of the microperforations, preferably substantially equal to 2 times the size of the microperforations. The production of circular microperforations in very large numbers has several disadvantages: The cycle time per microperforation performed is quite long, this being due to the circular shape of the microperforations. Conventionally, this shape is obtained by making concentric circles with the laser, or by circular scanning of the contour of the circle with the laser and then scanning by rectilinear trajectories inside the defined contour. These two options lead to having a significant cycle time per microperforation.Given the large number of microperforations that can be made at the level of a panel to obtain the desired visual effect (taking into account the size of the microperforations and their spacing on a surface as described above), and which can be at least 4 microperforations per mm 2 < , or 40,000 microperforations on a square surface with sides of 100 millimeters, the cycle time to obtain the final bodywork panel can be significant (the problem of the significant cycle time appearing when at least 5,000 to 10,000 microperforations are made, while knowing that the cycle time is desired to be less than 5 minutes, preferably between 1 and 2 minutes). The programming of the robot carrying the laser is quite complex, which leads to obtaining heavy programming files and therefore difficult to process by the machine.

[0007] The invention aims in particular to remedy these problems by proposing a method making it possible to reduce the cycle time for producing microperforations, and therefore the cycle time for manufacturing the final decorated panel.

[0008] To this end, the invention relates to a method for manufacturing a motor vehicle body part comprising the following steps: depositing at least one opaque coating on at least part of one face of a main body of the bodywork part, the main body being made of transparent or translucent plastic material, and producing a set of microperforations of the opaque coating by removing the opaque coating using a laser beam locally irradiating the coating, an irradiation path of the laser beam consisting solely of successive, substantially rectilinear trajectory lines.

[0009] The term "transparent" or "translucent" means that a part is at least transparent or translucent to any light radiation with a wavelength in the visible spectrum, i.e. between approximately 380 and 780 nm, or to any infrared radiation, i.e. with a wavelength between approximately 780 nm and 1 mm.

[0010] Microperforations are understood to mean the removal of the paint layer of a layer whose largest dimension of the irradiated surface is between 20 and 1000 µm, preferably between 50 and 700 µm, preferably between 100 and 300 µm.

[0011] “Local irradiation” means removal of material over the entire thickness of the coating. The coating may be a paint, for example in three layers (a primer 5 to 20 µm thick, a base 10 to 40 µm thick and a varnish 25 to 40 µm thick, i.e. a total thickness of between 40 and 100 µm), a metallization coating with a thickness that may be between 1 and 5 µm, a printed ink, a coating deposited by pad printing or screen printing, a film applied to the bodywork part (and comprising an ink, paint, etc.), etc. Laser irradiation makes it possible to remove the coating over its entire thickness (or the coating present on the film in the case of application of a film, the film acting as a support for the coating), for example in a thickness range of between 1 and 100 µm for the thickness examples above.

[0012] Thus, producing microperforations solely by irradiation trajectories comprising only substantially rectilinear trajectory lines saves time by simplifying the trajectory compared to a trajectory according to the prior art which is much more complex and mixes rectilinear and curved lines. In addition, programming a trajectory comprising only rectilinear movements is less complex to carry out and more easily processed by a machine than that according to the prior art.

[0013] Depending on other optional characteristics of the manufacturing process taken alone or in combination: the irradiation trajectory comprises at least in part the repetition of the same pattern of trajectory lines composed of several successive substantially rectilinear trajectory lines; at least one trajectory line is composed of irradiation sections and non-irradiation sections of the opaque coating so as to allow at least part of several microperforations to be produced; a focal distance between a source of emission of the laser beam and the face of the bodywork part is greater than or equal to between 100 and 1,000 millimeters, preferably between 300 and 700 millimeters, preferably between 400 and 600 millimeters; the focal distance between the source of emission of the laser beam and the face of the bodywork part is modified within the irradiation trajectory of the face of the bodywork part;at least a portion of the microperforations is substantially parallelogram-shaped, preferably substantially square or substantially rectangular in shape; a width of a scanning band of the laser beam on the face of the bodywork part is between 40 and 200µm, preferably between 70 and 120µm, preferably substantially equal to 100µm the opaque coating is formed by at least one layer of paint, a printed ink, a metallization coating, a coating deposited by pad printing or by screen printing; ;

[0014] The invention also relates to a device for manufacturing a motor vehicle body part comprising: at least one member for depositing at least one opaque coating on at least part of a face of a main body of the bodywork part, the main body being made of transparent or translucent plastic material, and at least one source emitting a laser beam configured to produce a set of microperforations of the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, the source emitting the laser beam being configured to produce an irradiation trajectory of the laser beam consisting solely of lines of successive trajectories that are substantially rectilinear.

[0015] Advantageously, the laser beam emitting source is configured to vary the focal distance between the laser beam emitting source and the face of the bodywork part during irradiation of the face of the bodywork part. Brief description of the figures

[0016] The invention will be better understood from reading the following description, given solely by way of example and with reference to the appended drawings in which: [ Fig. 1 ] is a view of a body panel comprising microperforations made by a method according to the invention, [ Fig. 2 ] is a view of a portion of an area comprising microperforations made by a method according to the invention, [ Fig. 3 ] is a representation of a microperforation made by a method according to a first embodiment of the invention, [ Fig. 4 ] is a representation of a microperforation made by a method according to a second embodiment of the invention, and [ Fig. 5 ] is a representation of a set of microperforations comparable to the microperforation of the Figure 4 . Detailed description

[0017] It has been represented on the Figure 1a bodywork part 2 comprising a transparent or translucent main body 3 and microperforation zones 4 produced by a method according to the invention, as well as Figure 2 illustrating a portion of a zone 4 of microperforations comprising a set of microperforations (here second microperforations 10 as described below).

[0018] Body part 2 is, in the example illustrated on the Figure 1 , a front bumper. Of course, it can also be any other body part, for example a tailgate, a grille, a rear bumper, etc. It could also be a part attached to a body panel.

[0019] Body part 2 of the Figure 1includes two microperforation zones. Of course, the number of microperforation zones 4 can be different, as can the size(s) of the microperforation zones 4. The microperforation zones 4 can be the same size or different sizes, include a greater or lesser number of microperforations, etc.

[0020] The microperforation zones 4 can be made on an external face 6 and / or on an internal face (not visible on the Figure 1 ) of the body part 2. The external face 6 means the face of the body part 2 visible from the outside of the vehicle when the body part 2 is mounted on a vehicle. The internal face means the face of the body part 2 opposite the external face 36, and not visible from the outside of the vehicle when the body part 2 is mounted on a vehicle.

[0021] The microperforations of a microperforation zone 4 are distributed at the level of the microperforation zone 4 (the Figure 2illustrates three lines of five microperforations), have one or more different shapes, a transparency (or translucency) allowing the radiation emitted by a source of visible light or infrared radiation and emitted from the rear of the bodywork part 2 (i.e. facing the internal face of the bodywork panel 2) to pass through, while not allowing one to see through the bodywork panel 2, in particular when a visible light source is inactive. As a reminder, the term "transparent", respectively "translucent", means that a part is at least transparent, respectively translucent, to any light radiation having a wavelength included in the visible spectrum, i.e. between approximately 380 and 780 nm, or to any infrared radiation, i.e. with a wavelength between approximately 780 nm and 1 mm.The visible light source is preferably an optical device comprising light-emitting diodes (LEDs). The infrared radiation source may be a LIDAR.

[0022] The body part 2 is made using a material that is transparent or translucent to light, such as, by way of example and in a non-exclusive manner: Polycarbonate (PC), Polymethyl Methacrylate (PMMA), Styrene Butadiene Acrylonitrile (ABS) or Styrene Acrylate (SAN), Acrylonitrile Styrene Acrylate (ASA) and their blends, amorphous polyolefins such as cycloolefin copolymers (COC) or cycloolefin polymers (COP), Polyethylene Terephthalate (PET), Polypropylene (PP), Polyamide (PA), Polybutylene Terephthalate (PBT), Polyurethane (PU), and Polyvinyl Chloride (PVC).

[0023] The method for producing the bodywork part 2 (injection or thermoforming for example) or the dimensions and shapes of the bodywork part 2 are known to those skilled in the art and will not be the subject of a detailed description here.

[0024] The manufacturing method according to the invention comprises the following steps: Deposition of at least one opaque coating on at least a portion of a face of the main body 3 of the bodywork part 2. This may for example be a paint (composed of a single layer or several layers), an ink, etc., as described previously. Generally, this is a coating which does not allow visible light or infrared radiation emitted by the source placed behind the bodywork part 2 to pass through and from which it is possible to locally remove the layer(s) of opaque material by using a laser beam. This deposition may be carried out on the external face 6 or on the internal face of the bodywork part 2. Production of a set of microperforations of the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, an irradiation path of the laser beam consisting solely of successive substantially rectilinear path lines.In the context of the invention, a laser beam irradiates a portion of the opaque coating to effect a total removal, in the thickness (according to the definition provided previously), of the opaque coating at the level of the zone(s) 4 of microperforations of the latter in order to obtain transparent or translucent microperforations as described above. This removal of the opaque coating makes it possible to uncover the main body 3, itself transparent or translucent. Visible light or infrared radiation will therefore be able to pass through the bodywork part 2, here the bodywork panel 2, at the level of the microperforations.

[0025] The size of the microperforations and their arrangement relative to each other (for example the distance between two adjacent microperforations) are chosen so as to obtain the desired effect described above, namely to allow the emitted radiation to pass through without seeing through the bodywork part 2 from the outside, in particular when a visible light source is switched off. The source of the laser beam is configured to obtain microperforations of the desired shape(s) and size(s), the desired spacing between the microperforations or even a desired transparency at the microperforations. The parameters set are in particular the following: The focal distance between the laser beam source and the body part 2. The power of the laser beam. The scanning speed of the microperforation zones 4. The exposure time of an area to be irradiated using a laser beam. The overlap or not of trajectory lines, as well as the percentage of overlap between trajectory lines. The alternation or not of trajectory lines corresponding to irradiation or not, or the presence within the same trajectory line of irradiation and non-irradiation sections. The frequency of the laser when the laser is a pulsed laser. The wavelength of the laser source.

[0026] THE figures 3 And 4 illustrate two microperforations 8 and 10 of different shapes. The Figure 3illustrates a first microperforation 8 according to a first embodiment of the invention, here of any shape. A first trajectory 12, comprising only first trajectory lines 12' (two referenced on the Figure 3 ) substantially rectilinear, makes it possible to obtain the first microperforation 8. The first trajectory 12 is made up of several first trajectory lines 12' which may or may not be similar and which make it possible to obtain a first irradiated surface 14, forming the first microperforation 8.

[0027] There Figure 4 illustrates a second microperforation 10 according to a second embodiment of the invention. A second trajectory 16, comprising only second trajectory lines 16' (two referenced on the Figure 4) substantially rectilinear, makes it possible to obtain the second microperforation 10. The second trajectory 16 is made up of several trajectory lines having substantially identical and aligned sections in order to obtain a second irradiated zone 18 of rectangular shape. According to the second embodiment of the invention, the irradiation trajectory (here the second irradiation trajectory 16) comprises at least in part the repetition of the same pattern 20 of trajectory lines composed of several trajectory lines (here the second trajectory lines 16') successive rectilinear (two successive patterns 20 are referenced on the Figure 1 ). Repeating the same pattern makes it even easier to program the movements of the laser beam source.

[0028] There Figure 5illustrates a set of second microperforations 10 forming two groups of aligned second microperforations 10. Together, these eight perforations 10 form at least a portion of a microperforation zone 4. In this example, a third trajectory line 22 makes it possible to produce an entire line of second microperforations 10. Of course, the number of trajectories for producing a set of microperforations can vary. It would be possible, for example, to produce all the microperforations illustrated in the Figure 5 through a single trajectory.

[0029] The third trajectory 22 is composed, like the first and second trajectories 12 and 16, of third rectilinear trajectory lines 22'. However, at least a portion of the third trajectory lines 22' (the horizontal trajectory lines on the Figure 4) comprises irradiation sections 24' and non-irradiation sections 24". In this embodiment, the alternation of irradiation sections 24' and non-irradiation sections 24" allows at least a third trajectory line 22' (the horizontal trajectory lines on the Figure 4 ) allows the production of at least part of several second microperforations 10. In the example of the Figure 4 , all the third horizontal trajectory lines 22' participate in the production of the second microperforations 10 of the same group of microperforations by alternating the irradiation 24' and non-irradiation 24" sections. An alignment of at least part of the second microperforations 10 makes it easier to pool the production of said microperforations.

[0030] Preferably, the focal distance between a source of emission of the laser beam and the face of the bodywork part is between 100 and 1000 millimeters, preferably between 300 and 700 millimeters, preferably between 400 and 600 millimeters. The establishment of a high focal distance makes it possible to obtain a point of impact of the laser beam on the bodywork part 2 of larger dimensions, and therefore to limit the number and / or the amplitude of movements of the laser beam to be implemented to produce one or more microperforations.A long focal length also makes it possible to scan a larger area of the bodywork part 2 by simple movements of the lens(es) of the laser source without having to move the laser beam source too often from one area to be scanned to another (movement necessary when the laser beam source reaches its spatial limit for treating an area of the bodywork part 2 by simple movements of the lens). An angular movement of the laser beam is therefore preferred while a member carrying the laser beam source, for example a robot arm, is fixed. The movements of said carrying member are thus limited by increasing the surface area that can be irradiated by simple movement of the lens of the laser beam source. It is even possible to reduce the number of laser beam sources to be used to treat a given surface within a given time that must be respected.

[0031] It is possible to make a shape of microperforations easily achievable by a trajectory according to the invention, in order to further reduce the manufacturing time of the bodywork part 2. At least a part of the microperforations has a shape of which at least one side is parallel to a trajectory line. This is the case for the microperforations of the figures 2 has 5 . Preferably, at least a portion of the microperforations are substantially parallelogram-shaped, preferably square or substantially rectangular. These are very simple shapes to produce by a method according to the invention, as demonstrated by the simple irradiation trajectories on the figures 3 And 4As explained previously, it may be interesting to have a point of impact of the laser beam on the face of the bodywork part that is quite large for the reasons mentioned above (increasing the size of an irradiated surface by simple angular movements of the lens). More generally, it is interesting to determine a size of the point of impact that makes it possible to optimize the scanning of an area to be irradiated, while ensuring a size that makes it possible to produce microperforations of the desired shape, while respecting the irradiation speeds, the irradiation times or even the overlap between two irradiation trajectory lines. To do this, the width of a scanning band of the laser beam on the face of the bodywork part is between 40 and 200 µm, preferably between 70 and 120 µm, preferably substantially equal to 100 µm

[0032] The invention also relates to a device for manufacturing a vehicle part comprising: At least one member for depositing at least one opaque coating on at least a portion of a face of a main body 3 of the bodywork part 2, the main body 3 being made of transparent or translucent plastic material. It may be a paint application robot, or means for depositing an opaque film. At least one source emitting a laser beam configured to produce a set of microperforations of the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, the source emitting the laser beam being configured to produce an irradiation trajectory of the laser beam consisting solely of lines of successive trajectories that are substantially rectilinear.

[0033] Advantageously, the emitting source of the laser beam is configured to be able to vary the focal distance between the emitting source of the laser beam and the face of the bodywork part 2 during the irradiation of the face of the bodywork part 2, for reasons mentioned above. List of references

[0034] 2: body part 3: main body 4: microperforation zones 6: external face 8: first microperforation 10: second microperforation 12: first trajectory 12': first trajectory lines 14: first irradiated surface 16: second trajectory 16': second trajectory lines 18: second irradiated surface 20: trajectory line patterns 22: third trajectory 22': third trajectory lines 24': irradiation sections 24": non-irradiation sections

Claims

1. Method of manufacturing a body part (2) of a motor vehicle characterized in that it comprises the following steps: - depositing at least one opaque coating on at least a portion of a face (6) of a main body (3) of the bodywork part (2), the main body (3) being made of transparent or translucent plastic material, and - producing a set of microperforations (8, 10) of the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, an irradiation path (12, 16, 22) of the laser beam consisting solely of successive substantially rectilinear path lines (12', 16', 22').

2. Manufacturing method according to claim 1, in which the irradiation trajectory (12, 16, 22) comprises at least in part the repetition of the same pattern of trajectory lines (20) composed of several successive trajectory lines (16') which are substantially rectilinear.

3. Manufacturing method according to any one of the preceding claims, in which at least one trajectory line (22') is composed of irradiation sections (24') and non-irradiation sections (24") of the opaque coating so as to allow at least part of several microperforations (10) to be produced.

4. Manufacturing method according to any one of the preceding claims, in which a focal distance between a source of emission of the laser beam and the face (6) of the bodywork part (2) is greater than or equal to between 100 and 1000 millimeters, preferably between 300 and 700 millimeters, preferably between 400 and 600 millimeters.

5. Manufacturing method according to any one of the preceding claims, in which the focal distance between the emission source of the laser beam and the face (6) of the bodywork part (2) is modified within the irradiation path (12, 16, 22) of the face (6) of the bodywork part (2).

6. Manufacturing method according to any one of the preceding claims, in which at least a portion of the microperforations (8, 10) are substantially parallelogram-shaped, preferably substantially square or substantially rectangular in shape.

7. Manufacturing method according to any one of the preceding claims, wherein a width of a scanning band of the laser beam on the face of the bodywork part is between 40 and 200µm, preferably between 70 and 120µm, preferably substantially equal to 100µm.

8. Manufacturing method according to any one of the preceding claims, in which the opaque coating is formed by at least one layer of paint, a printed ink, a metallization coating, a coating deposited by pad printing or by screen printing.

9. Device for manufacturing a motor vehicle body part comprising: - At least one member for depositing at least one opaque coating on at least a portion of a face (6) of a main body (3) of the body part (2), the main body (3) being made of transparent or translucent plastic material, and - At least one source emitting a laser beam configured to produce a set of microperforations of the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, the source emitting the laser beam being configured to produce an irradiation trajectory (12, 16, 22) of the laser beam consisting solely of successive substantially rectilinear trajectory lines (12', 16', 22').

10. Manufacturing device according to the preceding claim, in which the emitting source of the laser beam is configured to vary the focal distance between the emitting source of the laser beam and the face (6) of the bodywork part (2) during the irradiation of the face (6) of the bodywork part (2).

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